CAPLfunctionC2xReceivePacket

C2xReceivePacket

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CAPL Functions » Car2x » C2xReceivePacket

Function Syntax

long C2xReceivePacket( char *onPacketCallback );

Description

Use this function to register a CAPL callback to receive WLAN packets. The callback has a packet handle as parameter and the functions to access the tokens can be used. The C2xGetThis-functions can be used to access the payload of the highest interpretable protocol.

The callback must have the following signature:

void <OnC2xPacket> ( long channel, long dir, long radioChannel, long signalStrength, long signalQuality, long packet )

Parameters

• onPacketCallback: Name of CAPL callback

Return Values

• 0: Success
• ≠0: Error code

Example

Node System - PreStart in CAPL Browser

on preStart
{
  C2xReceivePacket("OnC2xPacket");
}

Node Callback Function in CAPL Browser

void OnC2xPacket( long channel, long dir, long radioChannel, long signalStrength, long signalQuality, long packet )
{
  byte rx_data[1500];
  byte rx_packet[1500];
  long rx_length;
  long rx_headerLength;

  rx_headerLength = C2xGetTokenData(packet, "wlan", "header", elCount(rx_packet), rx_packet);
  // without Ethernet header
  rx_length = C2xGetTokenData(packet, "eth", "data", elCount(rx_data), rx_data);
  write ("rx_headerLength: %d", rx_headerLength);
  write ("rx_dataLength: %d", rx_length);
  memcpy_off(rx_packet, rx_headerLength, rx_data, 0, rx_length);
  rx_length += rx_headerLength;
  // Always use rx_length to access rx_packet!
  write ("rx_length: %d", rx_length);
}